This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In order to gain understanding on the assembly and maintenance of the nuclear pore complex it is of interest to determine the turnover of its components. Using heavy-isotope metabolic labeling, immunoisolation of the Nup107 protein complex after increasing lengths of time (0, 3, 6, 10, 15, 22, and 32 hours)in cell culture, and mass spectrometry, we followed the half-lives of Nup107 and associated proteins.